scholarly journals Thermal analysis of end pumped fiber lasers subjected to jacket fluid cooling

2019 ◽  
pp. 311-311
Author(s):  
Haj El ◽  
Han Bani ◽  
Israa Al-Sawafta ◽  
Ahmad Sedaghat ◽  
M. Alshabi ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Fiber Lasers ◽  
Brinkman Number ◽  
Dimensionless Form ◽  
Water Jacket ◽  
Cooling Method ◽  
Radial Heat ◽  
The Common ◽  
Fluid Cooling ◽  
Axial Heat

End pumped lasers are highly efficient lasers particularly in diode lasers using micro lenses. The common cooling method for end-pumped systems is using water jacket or copper tube surrounding the laser rod. In this paper, the temperature distribution within a water jacket and a fiber laser end pumped by a top hat beam is studied analytically. The temperature distribution is obtained by considering the radial heat convection with fully developed laminar flow neglecting the axial heat conduction. The effect of laser dimensions and the Brinkman number on the temperature distribution are presented. The results indicate that the temperature distribution is strongly dependent on the Brinkman number. The results are presented in dimensionless form so that they can be applied to any end-pumped laser rod and fluid types. The main output of this work is that it is better for cooling purposes to have low Br values.

Nusselt Numbers in Rectangular Ducts With Laminar Viscous Dissipation

1999 ◽  
Vol 121 (4) ◽  
pp. 1083-1087 ◽  
Author(s):  
G. L. Morini ◽  
M. Spiga
Keyword(s):  
Boundary Condition ◽  
Temperature Distribution ◽  
Viscous Dissipation ◽  
Integral Transforms ◽  
Navier Stokes ◽  
Brinkman Number ◽  
Balance Equations ◽  
Nusselt Numbers ◽  
Finite Integral ◽  
Axial Heat

In this paper, the steady temperature distribution and the Nusselt numbers are analytically determined for a Newtonian incompressible fluid in a rectangular duct, in fully developed laminar flow with viscous dissipation, for any combination of heated and adiabatic sides of the duct, in H1 boundary condition, and neglecting the axial heat conduction in the fluid. The Navier-Stokes and the energy balance equations are solved using the technique of the finite integral transforms. For a duct with four uniformly heated sides (4 version), the temperature distribution and the Nusselt numbers are obtained as a function of the aspect ratio and of the Brinkman number and presented in graphs and tables. Finally it is proved that the temperature field in a fully developed T boundary condition can be obtained as a particular case of the H1 problem and that the corresponding Nusselt numbers do not depend on the Brinkman number.

Enhancement of RF Ablation by Combined Use of Ultra-Low Temperature Fluid Cooling and Magnetic Nanoparticles

2010 ◽  
Author(s):  
Zhong-Shan Deng ◽  
Jing Liu
Keyword(s):  
Magnetic Nanoparticles ◽  
Low Temperature ◽  
Bioheat Transfer ◽  
Rf Ablation ◽  
High Electrical Conductivity ◽  
Thermal Coagulation ◽  
Cooling Method ◽  
Tumor Tissues ◽  
Combined Use ◽  
Fluid Cooling

Magnetic nanoparticles with high electrical conductivity have been proved to be effective in enhancing the efficacy of RF ablation. However, the possible carbonization of tissues is an unfavorable factor in achieving greater dimensions of necrosis, because carbonized tissue is a poor conductor, increases impedance and limits propagation area of RF energy. To prevent potential carbonization of tissues surrounding to the heating part of RF electrodes during RF ablation, a new method using ultra-low temperature fluid was proposed for cooling RF electrodes and tissues in the vicinity of RF electrodes in this study. To test its feasibility, the corresponding bioheat transfer process during RF ablation simultaneously applying this cooling method and magnetic nanoparticles was studied through numerical simulations. The results indicate that the cooling method by ultra-low temperature fluid can prevent carbonization of tissues resulted by local high temperature, significantly enlarge the effective heating area and thus actualize highly efficient thermal coagulation to tumor tissues during RF ablation with adjuvant use of magnetic nanoparticles.

scholarly journals Temperature Profiles in a Micro Processor Cooled by Direct Refrigerant Evaporation

2016 ◽  
Vol 22 (3) ◽  
pp. 111-126
Author(s):  
Zygmimt Lipnicki ◽  
Haima Lechów ◽  
Kataizyna Pantoł
Keyword(s):  
Temperature Distribution ◽  
Analytical Solution ◽  
Theoretical Analysis ◽  
Temperature Profiles ◽  
Stationary Model ◽  
Cooling Systems ◽  
Cooling Method ◽  
External Cooling ◽  
Liquid Evaporation

Abstract Ail analytical solution to the equation for cooling of a unit, in the interior of which heat is generated, is presented. For that reason, a simplified non-stationary model for determination of the temperature distribution within the unit, temperature of the contact between unit and a liquid layer, and the evaporating layer thickness in the function of time, is elaborated. A theoretical analysis of the external cooling of the unit, by considering the phenomenon of the liquid evaporation with the use of the Fourier and Poisson’s equations, is given. Both, stationary- and non-stationary description of the cooling are shown. The obtained results of simulation seems to be useful in designing the similar cooling systems. A calculation mode for a cooling systems equipped with the compressor heat pump, as an effective cooling method, is also performed.

A Numerical Thermoplastic Analysis of Line Heating Processes for Saddle-type Shells with the Application of an Artificial Neural Network

1999 ◽  
Vol 15 (01) ◽  
pp. 10-20
Author(s):  
Jong Gye Shin ◽  
Jang Hyun Lee ◽  
Sung Kun Park
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Plastic Deformation ◽  
Temperature Distribution ◽  
Flat Plate ◽  
Three Dimensional ◽  
Published Data ◽  
Line Heating ◽  
Cooling Method ◽  
Saddle Type

Line heating (LH) is a process for forming compound-curved shells of a ship's hull, and is carried out by skilled workers. The accuracy of final shape and the production time are based solely on the experience and intuition of the workers. Many attempts have been tried to analyze the LH mechanism theoretically and experimentally, in order to achieve productivity. The nature of the LH process involves a three-dimensional transient thermal conduction phenomenon, followed by temperature-induced permanent plastic deformation. Due to the complexity of the physical problem, a theoretical analysis is not presently available. Previous studies have been limited to simplified models or two-dimensional analyses, which are inadequate for applications in current shipyard practices. In addition, a final manufactured shape is dependent on many factors involved in the process, such as torch speed and position, type of heat, cooling method (air or water), as well as plate dimensions. The effect of each factor on a final deformed shape con not be obtained using simplified modeling. With a practical application in mind, a numerical approach was employed, to simulate the LH process. Based on the mechanics of LH, temperature and stress fields are uncoupled, and each field is solved using a general finite element program. Heat flux for the heating torch and convection condition for the cooling hose are modeled for temperature analysis. The plate to be fabricated is descretized using three-dimensional solid elements. In order to verify the validity of the present model, a temperature distribution is obtained for a flat plate problem and compared with published data. The results are in good agreement with the published data. A numerical simulation is then carried out for forming saddle-type shells according to current shipyard practices. Currently, the line heating is applied to a cylindrically curved shell to produce a doubly curved shape, that is saddle-type shell. Thus, singly curved shells are modeled to simulate the forming process of saddle-type shells and temperature distribution, permanent plastic deformation, and residual stress are calculated for the obtained final shells. Parametric studies are given and discussed relative to the effects of forming parameters, such as torch speed, cooling method, and plate dimensions. It should be noted that each piece of shell of a ship's hull is not identical. In addition, each ship is different. This means that every single piece of flat plate is fabricated using different combination of forming parameters. Thus, it is necessary to generate new parameters from the calculated results for the automation of the LH process. An artificial neural network (ANN) algorithm is applied to generate new parameters, and is verified with several actual examples.

Evaluation of Thermal Shock Fracture Toughness for ATJ Graphite Using Laser Irradiation Method

2004 ◽  
Vol 261-263 ◽  
pp. 93-98 ◽  
Author(s):  
Jae Hoon Kim ◽  
Young Shin Lee ◽  
Duck Hoi Kim ◽  
N.S. Park ◽  
Soon Il Moon
Keyword(s):  
Fracture Toughness ◽  
Temperature Distribution ◽  
Thermal Shock ◽  
Laser Irradiation ◽  
Laser Power ◽  
Laser Source ◽  
Surface Phenomenon ◽  
Heat Resistant ◽  
The Common ◽  
Fracture Toughness Specimen

Graphite has been developed as heat resistant material. To apply a reliable structural design using graphite, it is very important to investigate thermal shock characteristics. The common experimental methods of thermal shock fracture toughness are quenching and arc discharging heating methods. This paper describes experimental technique to evaluate the thermal shock fracture toughness using laser irradiation and proposes that a critical value of laser power can be a measurement to evaluate heat resistant materials. The laser source is CO2 laser having maximum power of 4.0kW. The range of laser beam is from 1.0 to 2.7 kW and the beam duration is fixed at 1sec. K and C type thermocouples were used to measure the temperature distribution of a thermal shock fracture toughness specimen. In this study, the temperature distribution of specimen surfaces and critical laser power was investigated. After test, the surface phenomenon of specimen is examined using radiography and SEM. It is concluded that the critical laser power causing fracture can be the major factor of thermal shock fracture toughness of ATJ graphite.

Water Jacket Spacer for Improvement of Cylinder Bore Temperature Distribution

2005 ◽  
Author(s):  
Takashi Matsutani ◽  
Takanori Nakada ◽  
Yoshikazu Shinpo ◽  
Makoto Hatano
Keyword(s):  
Temperature Distribution ◽  
Water Jacket ◽  
Cylinder Bore

Investigation on Cooling System of High-Concentration Photovoltaic with Oscillating Heat Pipe

2012 ◽  
Vol 512-515 ◽  
pp. 84-89
Author(s):  
Wen Guang Geng ◽  
Ling Gao ◽  
Min Shao ◽  
Dong Ling Yuan ◽  
Xuan You Li
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Heat Pipe ◽  
Cooling System ◽  
Numerical Study ◽  
Navier Stokes ◽  
Turbulent Model ◽  
High Concentration ◽  
Oscillating Heat Pipe ◽  
Cooling Method

Cooling of concentration photovoltaic (CPV) cells with oscillating heat pipe was investigated numerically and experimentally. Based on Reynolds-averaged Navier-Stokes approach, a turbulent model was proposed in present work. Numerical study presented the temperature distribution under different heat flux and various outdoor conditions. CPV (with 12 suns concentration) system was experimentally studied, and the results show that the oscillating heat pipe begin operation at about 62°C, and CPV system could enhance electric power with a good cooling system under a high concentration light. The oscillating heat pipe cooling system, without air fan or pump, no power consumption, gives a uniform, reliable, simple and costless cooling method, oscillating heat pipe cooling is suitable for the high-CPV system.

scholarly journals 3-D Conjugate Flow and Heat Transfer Calculations of a Film-Cooled Turbine Guide Vane at Different Operation Conditions

1997 ◽  
Author(s):  
Dieter E. Bohn ◽  
Volker J. Becker ◽  
Karsten A. Kusterer
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Leading Edge ◽  
Equilibrium Temperature ◽  
Flow And Heat Transfer ◽  
Cooling Method ◽  
Thermal Investigations ◽  
Transfer Method ◽  
Cooling Air ◽  
Operating Points

Film-cooling has become a widely used cooling method in present day gas turbines. Cooling gas ejection at the leading edge serves to protect the entire vane surface from contact with the hot gas. Thus, material temperatures must be reduced in order to guarantee an economically acceptable life span of the vane. Normally, thermal investigations are performed with frozen equilibrium temperature distributions for different operating points. Thus, the heat transfer interaction between the flow and the solid body is neglected. This influence is taken into account by a conjugate fluid flow and heat transfer method in the investigations to be presented. In the case of the aerodynamics, a solver for the 3-D full Navier-Stokes equations is employed. The numerical scheme works on the basis of an implicit finite volume method combined with a multi-block technique. In the 3-D numerical experiment to be presented, the influence of leading edge cooling gas ejection on the temperature distribution to the vane material is investigated. The cooling air is ejected through two slots at the leading edge. 3-D aerodynamic investigations performed by Bohn et al. (1996a) have shown the influence of complex 3-D flow phenomena, e.g. secondary flow, on the distribution of the cooling air along the vane surface. Furthermore, 3-D thermal investigations for one operation point with a realistic temperature ratio of cooling air flow and main flow were presented by Bohn et al. (1996b). The investigations were performed for three different flow angles in the non-ejection case and the film-cooled case in order to demonstrate the operation of the cooling method. The shift of the stagnation line significantly influences the cooling fluid distribution along the vane surface, something that has consequences for the thermal load of the vane. Furthermore, the results are compared to an investigation with a prescribed frozen equilibrium temperature distribution. It is shown that the vane temperature increases locally for over 10 K at different operating points. This increase is significant for the thermal design process and can only be detected using the conjugate fluid flow and heat transfer method.

scholarly journals Pulsed rapid cooling method of the massive relating to heat bodies

2018 ◽  
pp. 61-65
Author(s):  
I. A. Pribytkov ◽  
A. Yu. Terekhova ◽  
S. I. Kondrashenko
Keyword(s):  
Elevated Temperature ◽  
Temperature Distribution ◽  
Main Part ◽  
Rapid Heating ◽  
Rapid Cooling ◽  
Radial Temperature ◽  
Radial Temperature Distribution ◽  
Cooling Method ◽  
Cooling Conditions

The data are presented on the pulsed rapid enhanced cooling of the massive related to heat bodies. The pulsed rapid heating consisting of the alternating enhanced heating and retardation during which the main part of the heat applied to the metal by convection, supposes the elevated temperature raise rate just when heating. These cooling conditions influence substantially on the radial temperature distribution inside the metal during the cooling.Ill.5. Ref. 8.

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